1. Field of the Invention
The present invention relates to a method, program, and apparatus for copy protection, and more particularly to a method, program, and apparatus for detecting specific information representing prohibition of an output of image data included in image data of an original image. The present invention also relates to a computer-readable storage medium storing the above-mentioned program for detecting specific information representing prohibition of an output of image data included in image data of an original image.
2. Discussion of the Related Art
With recent improvements in image processing and image forming technologies, it has become possible that a high-tech digital color copying apparatus, for example, can reproduce a monetary document even with a high fidelity such that the reproduced image is hardly distinguishable from the original image. Such monetary document is a paper currency, a security, and the like, for example, and will not normally be placed as an object of copying since an authorized currency creation is illegal. Therefore, the high-tech digital color copying apparatus needs to be provided with a feature of prohibiting a reproduction of an anti-copy document such as a monetary document, a confidential document, etc. With this feature, a copy-prohibited document may be entirely prohibited from being reproduced or can be reproduced into a nonreadable image, for example.
In offices, there are many confidential documents which are not necessarily monetary documents but are prohibited from being copied from a viewpoint of trade secrets. These confidential documents also need to be prohibited from being copied with the high-tech digital color copying apparatuses.
Under these circumstances, various inventions associated with the above-mentioned high-tech digital color copying apparatus have been created to attempt to restrict the capability of an image reproduction with a high fidelity.
Japanese Laid-Open Unexamined Patent Application Publication, No. 6-125459 describes a technique for recognizing a special document such as currency, a security, and so on by comparing input image data with a prestored specific mark by pattern matching and judging that the input image data is a special document when the input image data is recognized as matching the prestored specific mark. Japanese Laid-Open Unexamined Patent Application Publication, No. 2001-086330 also describes a similar technique. If an input original is judged as a special document easily in this way, a reproduction of this document can readily be prohibited.
This technique accordingly requires a storage of reference pattern data to be applied to the copy protection for a specific document. However, it would be difficult to apply this reference pattern data, which is fixed data, to the copy protection for an indefinite number of general confidential documents.
As another example, Japanese Laid-Open Unexamined Patent Application Publication, No. 7-036317 describes a technique for recognizing a confidential document dealt with as a copy-prohibited document by detecting a specific mark such as “CONFIDENTIAL,” for example, printed on this confidential document indicative of its confidentiality. A print of such a specific mark indicating the document confidentiality in a confidential document is a common practice and the above-mentioned publication uses it. When an input original is judged as a special document easily in this way, a reproduction of this document can readily be prohibited. Japanese Laid-Open Unexamined Patent Application Publication, No. 7-087309 also describes a similar method.
However, when a confidential document has a print of a specific confidential mark such as “CONFIDENTIAL,” for example, a copy of this confidential document can easily be made by avoiding a print of the specific confidential mark by hiding it with a piece of paper, for example. Thus, the copy protection fails to protect the confidential document from copying.
Japanese Laid-Open Unexamined Patent Application Publication, No. 9-164739 also describes a similar technique for restricting a copying of document by embedding a watermark in an original image which is desired to be protected from copying. This technique uses a paper sheet having a specific background image to which an original image is attached. The specific background image includes a background dot pattern having a base area and a message area. From its nature, the background dot pattern is inconspicuous in comparison with the original image and therefore it does not cause a problem when reading the original image. This technique, however, causes the background dot pattern to appear when the original image having this background dot pattern is copied. The background dot pattern of this technique is provided with a word of warning such as a “NO COPYING”, for example, so that a copy of this original document is recognized easily at a glance as a confidential document for which it is desired to be protected from copying. Therefore, this technique has a psychological effect of restricting against the copying of the document.
However, this technique produces the above-mentioned psychological effect only after the copy is made. Therefore, for the persons who do not care about the appearance of the background dot pattern, the copy protection does not work at all.
There is another technique for prohibiting a reproduction of a copy-prohibited document which addresses the above-described problems. In this technique, when preparing an original image, a predetermined background dot pattern is embedded in a background image which is included in the image data of the original image. When scanning such an original image by a scanner, the background dot pattern is detected from the image data of the original image. Then, the detected background dot pattern is compared with a background dot pattern representing an anti-copy document which is stored in a predetermined storage area by a pattern matching method. If the detected background dot pattern matches with the background dot pattern representing an anti-copy document, the output of the image data of the original image is prohibited.
A flatbed scanner is generally used when scanning an original image. The flatbed scanner scans and reads an original image of an original sheet placed on a contact glass by moving a moving carriage, and has an image scaling function in which an image is scaled (i.e., magnified or reduced) in a sub-scanning direction. When an image scaling mode is selected by an operator, a background dot pattern included in the image data of an original image scanned by the scanner is also scaled. In this condition, the scaled background dot pattern does not match with the background dot pattern stored in the predetermined storage area, so that the pattern matching cannot be properly performed.
To perform the pattern matching properly, the following two methods are considered: (1) the image data of a scaled original image is normalized to its original size, then, a background dot pattern is detected from the normalized image data; and (2) a plurality of background dot patterns representing an anti-copy document are prepared such that the background dot patterns correspond to scaling ratios set when scanning an original image, and are stored in the predetermined storage area. One of the plurality of background dot patterns stored in the storage area is selected according to the scaling ratio set when scanning an original image, and is used when matching with the scaled background dot pattern included in the image data of the original image scanned by the scanner at a predetermined scaling ratio.
In the first method in which the image data of a scaled original image is normalized to its original size, the pattern matching can be properly performed when magnified image data is normalized to its original size. When normalizing reduced image data, an image is magnified in the sub-scanning direction. In this normalizing processing, the number of lines to be processed and a processing amount per unit time increase. As a result, real-time processing cannot be achieved.
In the second method in which a plurality of background dot patterns representing an anti-copy document are prepared, a large number of background dot patterns need to be prepared according to the scaling ratios. Especially in the magnification, the size of the background dot pattern increases. This causes the increase of a processing amount in the software processing performed when comparing the detected background dot pattern with the background dot pattern representing an anti-copy document, and the increase of the scale of a circuit which performs the software processing. As a result, a real-time processing cannot be achieved.
Therefore, as discovered by the present inventors, it is desirable to provide an image processing apparatus, a program, and a computer-readable storage medium that can perform a real-time processing in the matching of background dot patterns.
Further, in an image processing apparatus, real-time processing is required for image recognition processing, pattern matching processing, and image processing. Therefore, such processing is performed at a high speed by using an ASIC (Application Specific IC) and a processor specially used for image processing, such as a DSP (Digital Signal Processor) and a SIMD (Single Instruction Stream/Multiple Data Stream) processor.
Many Japanese Laid-Open Unexamined Patent Application Publications describe a load of a program or data into a special processor included in the above-described image processing apparatus.
For example, Japanese Laid-Open Unexamined Patent Application Publication, No. 9-244901 describes an image processing apparatus in which a compressed control program is stored in a storage unit, and is selectively decompressed. Japanese Laid-Open Unexamined Patent Application Publication, No. 9-128605 describes a control program for a vending machine which can be rewritten for enhancing maintenance. Japanese Laid-Open Unexamined Patent Application Publication, No. 9-244985 describes a computer system in which a control program is input through a network. Japanese Laid-Open Unexamined Patent Application Publication, No. 2000-123156 describes an image processing apparatus in which an image processing program corresponding to plural areas in image data is loaded into a digital signal processor, and the digital signal processor performs a specified image processing based on the program loaded into the digital signal processor. Japanese Laid-Open Unexamined Patent Application Publication, Nos. 2001-076125 and 2002-207606 describe an image processing apparatus in which image processing programs can be changed and added.
A special processor, such as a DSP and a SIMD processor, includes a program area and a data area for high-speed processing. When performing image recognition processing (e.g., a pattern matching processing) based on image data (e.g., a background dot pattern), an amount of processing program and dictionary data typically becomes large because the processing content of a processing program needs to be changed according to conditions (e.g., a scaling ratio) for reading images and dictionary data (for example, including background dot patterns as pattern matching references) referred for image recognition processing which needs to be changed. Because the capacity of the program area and data area of the special processor is limited, it is difficult to load all the processing program and dictionary data adapted to each condition for reading images into the program area and data area of the special processor in advance.
Therefore, as discovered by the present inventors, it is desirable to provide an image processing apparatus and method that can perform optimum image recognition processing without using a large storage capacity for a program area and data area in a special processor, such as a DSP and a SIMD processor.
In the above-described high-tech digital color copying apparatus, a function of prohibiting a reproduction of an anti-copy document such as a monetary document, a confidential document, etc., is often provided as an optional function for a user who has much concern for security. An anti-copy document detecting unit, such as a monetary document detecting unit, and a confidential document detecting unit, is provided with the copying apparatus as an optional unit. To avoid the illegal copy of monetary document, various techniques have been proposed. For example, Japanese Patent Nos. 2647566, 3032722, and 3032723, and Japanese Laid-Open Unexamined Patent Application Publication, Nos. 6-54185, 7-30748, and 7-322062 describe a technique that a copying operation is performed after a copying apparatus detects the attachment of a monetary document detecting unit to the copying apparatus.
Generally, when an optional function such as a confidential document detecting function, is required to add to a copying apparatus, a confidential document detecting unit or a board equipped with the confidential document detecting unit is attached to the copying apparatus. At this time, a control software program needs to be replaced. If the version number of the control software program increases, a test process increases, and the management of the control software program becomes complicated.
Therefore, as discovered by the present inventors, it is desirable to provide an image processing apparatus, a program, and a computer-readable storage medium that can use an anti-copy document detecting unit as an optional unit without complicated management of a control software program.